Photoluminescence can be divided into fluorescence and phosphorescence. When a material absorbs the energy of the external light, the electrons in the ground state in the material are excited to a excited state, at this moment if the energy is quickly released to a state of a minimum vibration, i.e. one of the excited states, and then is released back to the ground state in a form of light emission, and this phenomenon is called fluorescence; while if the energy is transferred by an intersystem crossing to an excited state with different self-spinning multiples, and released to a state of a minimum vibration, and then is released back to the ground state in a form of light emission, and this phenomenon is called phosphorescence. Currently the material able to generate fluorescence or phosphorescence can be divided into inorganic and organic materials. The organic fluorescence materials are usually transferred to a biological body by adopting the transgenic method. For instance, the natural fluorescence protein can be extracted from the bodies of thousands of Aequorea Victoria. This protein can emit green fluorescence, and is called green fluorescent protein (GFP). The research shows that the GFP has a special chromophore, which is a chemical functional group able to absorb and emit light. When radiated by the violet or blue light, the chromophore of the GFP absorbs the energy of the light and is excited, and then emits the light to release the energy, where the emitted light has a wavelength located within the wavelength range of the green light. Since some unanticipated risks of the gene transfer exist, the strict regulations for the gene transfer are setup specially for changing the gene composition of the biological body so as to avoid the damages on the other original biological bodies due to the gene escape.
Another type of inorganic fluorescence materials are fluorescence powders or various metal materials. Since the fluorescence powders have excellent illuminating efficiency, currently most of the illuminating devices adopt the fluorescence powders. The major raw materials of the fluorescence materials are rare earth elements. Since the rare earth elements are rare, and the governments of the countries of the reserve of the rare earth elements have conditionally limited their export. The prices of the rare earth elements grow every year. In additions, the rare earth elements have the issue of the toxicity to the environment according to the assess of the environmental reservation. Besides, the rare earth elements can cause serious damages on the biological bodies if applied thereinto.